1 Field of the Invention
The present invention relates to a file sheet storing device. More particularly, the present invention pertains to a file sheet storing device for storing a file sheet which is adapted to store a plurality of information carrying mediums such as a picture slides in rows and/or columns in a plane. The present invention specifically relates to a file sheet storing device including a plurality of covers each comprising a first sheet and a second sheet which are made of a transparent material and connected together at least at three sides to form a storing bag having an opening at the remaining side for insertion of the file sheet, the storing bag being provided along one of the sides with binding means for making it possible to bind the bag with the file sheet stored therein in a binder.
2 Description of the Prior Art
File sheets adapted to store information carrying mediums such as picture slides in rows and columns are widely used in view of conveniences that the information carrying mediums can be placed on a platen of an optical projector with the mediums held on the file sheet. The file sheet having a plurality of information carrying medium held thereon may be moved on the platen of the projector to place a desired one of the mediums at the projecting position.
It is desired for this type of file sheet to provide a protective covers for covering the both side surfaces of the file sheets so that the information carrying mediums stored thereon can be protected from any possible scratches and/or deposition of dusts thereon. It is also desired that the covers are of transparent material so that the information carrying mediums such as picture slides can be visually observed through the covers.
For the purpose, the Japanese utility model publication Hei 4-14225 which corresponds to the U.S. Pat. No. 4,997,089 issued on May 5, 1991 to the same inventor of the present invention discloses a dust cover for a file sheet. The dust cover of this patent is made of a transparent material and comprises a first sheet adapted to cover one side surface of the file sheet and a second sheet to cover the other side surface of the file sheet. The first and the second sheet of the cover are attached together along three sides leaving an inlet opening formed along the remaining side. A cover flap is provided at the side where the inlet opening is formed. The cover is further formed along the side opposite to the side where the inlet opening is formed with a plurality of cuts at locations corresponding to the binder holes formed in the file sheet which is to be stored in the cover so that the file sheet in the cover can be bound in a binder of a conventional structure.
The dust cover of the known structure has been found satisfactory to a substantial extent, however, problems have been experienced particularly in the case where the file sheets are of relatively rigid structure. It has been experienced that in the case where the file sheet stored in the dust cover is of a rigid structure there is a tendency that the file sheet is shifted in the dust cover under its own weight to a side of the dust cover so that the binder holes in the file sheet cannot be aligned with the cuts formed in the dust cover. In order to avoid such problem, binder holes may be formed in the dust cover along the side thereof. However, this structure is found disadvantageous in that the file sheet stored in the cover has a tendency of being shifted under its weight toward the side portion where the binder holes are provided with the result that the thickness at the side is increased to an extent that it may become difficult to turn the file sheet over another file sheet. This is particularly true in the case where the file sheet is of a relatively rigid structure.